i have my cav-plate about 1 inch above the keel when all the way down. with the prop im running i tend to be running the jack plate about 1-1/2 inches up... ive never had a problem with blow out or rough water but i am running a 4 blade prop with a good amount of cup. i can get on plane with the plate 4 inches up and stay on plane with it all the way up, but i start loosing water pressure around 4 inches... i